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.Dd February 15, 2020
.Dt USBA_HCDI_PIPE_OPEN 9E
.Os
.Sh NAME
.Nm usba_hcdi_pipe_open ,
.Nm usba_hcdi_pipe_close
.Nd open and close a USB pipe
.Sh SYNOPSIS
.In sys/usb/usba/hcdi.h
.Ft int
.Fo prefix_hcdi_pipe_open
.Fa "usba_pipe_handle_data_t *ph"
.Fa "usb_flags_t usb_flags"
.Fc
.Ft int
.Fo prefix_hcdi_pipe_close
.Fa "usba_pipe_handle_data_t *ph"
.Fa "usb_flags_t usb_flags"
.Fc
.Sh INTERFACE LEVEL
.Sy Volatile -
illumos USB HCD private function
.Pp
This is a private function that is not part of the stable DDI.
It may be removed or changed at any time.
.Sh PARAMETERS
.Bl -tag -width Fa
.It Fa ph
A pointer to a USB pipe handle as defined in
.Xr usba_pipe_handle_data 9S .
.It Fa usb_flags
Flags which describe how allocations should be performed.
Valid flags are:
.Bl -tag -width Sy
.It Sy USB_FLAGS_NOSLEEP
Do not block waiting for memory.
If memory is not available the allocation will fail.
.It Sy USB_FLAGS_SLEEP
Perform a blocking allocation.
If memory is not available, the function will wait until memory is made
available.
.Pp
Note, the request may still fail even if
.Sy USB_FLAGS_SLEEP
is specified.
.El
.El
.Sh DESCRIPTION
The
.Fn usba_hcdi_pipe_open
and
.Fn usba_hcdi_pipe_close
entry points are called by the USB framework whenever a client, or the
framework itself, need to open or close a specific pipe.
For additional background see
.Xr usba_hcdi 9E .
.Pp
When a pipe is opened, the host controller driver is responsible for
preparing the specified endpoint for performing transfers.
This may include allocating bandwidth, programming the controller, and more.
When the pipe is closed, the host controller driver is responsible for
cleaning up any resources that were allocated during the open call.
.Pp
The pipe handle,
.Fa ph ,
identifies the endpoint that it the USBA is trying to open or close
through its endpoint descriptor in the
.Sy p_ep
member.
The endpoint descriptor is described in
.Xr usb_ep_descr 9S .
From the endpoint descriptor the driver can determine the type of
endpoint, what the address of the endpoint is, and what direction the
endpoint is in.
When combined, these uniquely describe the pipe.
.Pp
To open a pipe, the driver may need additional companion endpoint
descriptors.
If these are available, they will be in the
.Sy p_xep
member of the pipe handle.
See
.Xr usb_ep_xdescr 9S
for more information on how to determine which descriptors are present
and get the information encoded in them.
.Pp
Host controller drivers should check the USB address of the
USB device that
.Fa ph
belongs to.
The driver may be asked to open a pipe to the root hub.
As the root hub is often synthetic, the driver may need to take a different
path than normal.
.Ss Pipe open specifics
A given endpoint on a device can only be opened once.
If there's a request to open an already open endpoint, then the request to open
the pipe should be failed.
.Pp
By the time the call to open a pipe returns, the driver should expect
that any of the pipe transfer or reset entry points will be called on
the pipe.
.Pp
A driver can establish private data on an endpoint.
During pipe open it may set the
.Sy p_hcd_private
member to any value.
Generally this points to an allocated structure that contains data specific to
the host controller.
This value will remain on the pipe handle.
It is the responsibility of the driver to clear the data when the pipe is
closed.
.Ss Pipe close specifics
When a pipe is closed, the driver must clean up all of the resources
that it allocated when opening the pipe.
For non-periodic transfers, the host controller driver may assume that there
are no outstanding transfers that need to be cleaned up.
However, the same is not true for periodic pipes.
.Pp
For pipes that have outstanding periodic transfers, the host controller
driver needs to clean them up and quiesce them as though a call to
either
.Xr usba_hcdi_pipe_stop_intr_polling 9E
or
.Xr usba_hcdi_pipe_stop_isoc_polling 9E
had been called.
.Pp
Just as with opening the pipe, the driver should pay attention to the
address of the USB device, as it may be the root hub, which may be a
synthetic pipe.
.Pp
When a call to
.Fn usba_hcdi_pipe_close
completes, the device should be in a state that the pipe can be opened
again.
.Sh RETURN VALUES
Upon successful completion, the
.Fn usba_hcdi_pipe_open
and
.Fn uba_hcdi_pipe_close
functions should return
.Sy USB_SUCCESS .
Otherwise, it should return the appropriate USB error.
If uncertain, use
.Sy USB_FAILURE .
.Sh SEE ALSO
.Xr usba_hcdi 9E ,
.Xr usba_hcdi_pipe_stop_intr_polling 9E ,
.Xr usba_hcdi_pipe_stop_isoc_polling 9E ,
.Xr usb_ep_descr 9S ,
.Xr usb_ep_xdescr 9S ,
.Xr usba_pipe_handle_data 9S
